Survival Improving for Kids on Dialysis

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Overall survival among children with end-stage renal disease who are being treated with dialysis has greatly improved over the last 20 years.

Note that although the magnitude of this improvement was greater for younger children than older children, the difference was not statistically significant.

WASHINGTON -- Overall survival among children with end-stage renal disease (ESRD) who are being treated with dialysis has greatly improved over the last 20 years, researchers said here.

Each 5-year increment in calendar year of dialysis initiation was associated with an adjusted hazard ratio for all-cause mortality of 0.80 (95% CI 0.75 to 0.85) among children younger than 5 years at initiation and an HR of 0.88 (95% CI 0.85 to 0.92) among those 5 years and older, Benjamin Laskin, MD, of Children's Hospital of Philadelphia reported here at the annual meeting of the Pediatric Academic Societies. The results also were published simultaneously online in JAMA.

Although the magnitude of this improvement was greater for younger children than older children, the difference was not statistically significant (interaction P=0.10), they reported.

"Numerous factors may have contributed to the observed reductions in mortality risk over time," Laskin and colleagues wrote.

Although all individuals with ESRD face a decreased life expectancy, "in no group of [ESRD] patients is the loss of potential years of life larger than in children and adolescents," the investigators noted in their introduction. And while kidney transplant is still the treatment of choice in these patients, three-quarters of children and adolescents who receive transplanted kidneys are treated with dialysis prior to receiving the transplant.

However, children on maintenance dialysis have all-cause mortality rates 30 times higher than the general pediatric population; cardiovascular disease and infection are the most common causes of death among children with ESRD, the authors wrote, citing a 2004 study. To see whether mortality rates in this group have improved in recent years, the researchers conducted a retrospective cohort study of 23,401 children and adolescents less than 21-years-old who had initially undergone dialysis treatment for ESRD.

Data on study participants were obtained from the U.S. Renal Data System database, which includes virtually all children treated for ESRD. All patients underwent dialysis sometime between January 1990 and the end of December 2010.

The study's primary outcome was all-cause mortality. Other outcomes looked at included cardiovascular and infection-related mortality.

The researchers found that higher mortality risk was independently associated both with glomerulonephritis as well as other types of primary renal disease -- as opposed to congenital kidney or urinary tract anomalies, the presence of one or more comorbidities, and lower estimated socioeconomic status in children at any age.

Looking specifically at cardiovascular mortality, each 5-year increment in calendar year of initiation of dialysis was associated with an adjusted HR of 0.54 (95% CI 0.47 to 0.63) among children younger than 5 years at initiation and an HR of 0.66 (95% CI, 0.61 to 0.70) among those 5 years and older.

One possible reason for the mortality decrease may just be better medical care overall for patients, Laskin told MedPage Today. But he added that there have been dialysis-specific improvements that could also play a role, including "smaller filters we can use, machines that can dialyze kids at home that have smaller fill volumes that are needed for children, and a lot more practice guidelines in [the] last 10 or 15 years focused not only on adults but also on kids. As more people are following those, we've seen improvement."

Interestingly, the researchers found few improvements in treatment occurring within the last 5 years, he added. "Most of it occurred beforehand, so we think there's a lag between the technology being developed, approved by the FDA, and then being implemented."

Despite these positive results, the goal of treating this group of children should be to get them transplants rather than to continue them longer on dialysis -- or better yet, to skip dialysis and go directly to the transplant, Mark Mitsnefes, MD, of Cincinnati Children's Hospital and a co-author of the study, told MedPage Today. "It looks like preemptive transplant is even better [in terms of outcomes] than when children first go on dialysis and then go on transplant."

Whatever improvements have been made on dialysis, Mitsnefes said, "are not enough because mortality is still high. New ways of dialysis should be done because what is done right now is just not enough."

Limitations of the study included possible confounding by variables not included in the database, possible changes over time in the reporting of certain variables, and the inclusion of "cardiac arrest (cause unknown)," which may include arrhythmias due to hyperkalemia, embolic events, or other noncardiac conditions, thereby resulting in overestimation of cardiovascular mortality rates, the authors noted.

The study was funded in part by the Health Resources and Services Administration.

Laskin reported links with Amgen and Genzyme.

Reviewed by Robert Jasmer, MD Associate Clinical Professor of Medicine, University of California, San Francisco and Dorothy Caputo, MA, BSN, RN, Nurse Planner

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